1. Field of the Invention
The present invention relates to a surge voltage preventing D-sub connector, and more particularly, to printers, repeaters, or other device that uses a connector cable that is coupled to a surge voltage preventing female-type D-sub connector usable in a computer, constructed so that the ground terminal is grounded before the signal terminal.
2. Description of the Background Art
In general, a D-sub connector is a computer connector, to which a connector cable of a printer, a repeater or another device may be coupled. A female-type connector and a male-type connector are intended to be coupled with each other. A female-type D-sub connector may have an array of twenty-five pinholes with the signal pinholes conventionally numbered one through seventeen, and the grounding pinholes conventionally numbered eighteen through twenty-five. An internal construction of the conventional D-Sub connector, as it now exists, includes a female-type connect pin located in each pin hole, to which a pin of a male-type connector will be coupled. The corresponding pins coincide with each other and electronic signal lines are coupled when a printer or other connector cable is inserted into the female D-sub connector.
In a conventional D-sub connector however, the length of the pins of the ground terminal and a signal terminal are the same. We have observed that if a user inserts a printer cable or a repeater cable obliquely into a connector, an electrical connection may be established via a signal line earlier than the electrical coupling between the ground pins of the cable and the ground terminal of the connector. Consequently, undesired noise superimposed upon the power conductors or a momentary voltage surge to the system may be generated by the ground signals occurring when the ground pins of the cable are subsequently coupled with the ground terminal, resulting in consequential damage to the input-output controlling chips.
One recent effort to implement the concept of sequential mating to protect the electronic components in a circuit may be noted in U.S. Pat. No. 5,268,592 to Bellamy. Bellamy however, is suitable principally for circuit cards in electronic circuit boards, and not for D-sub connectors, and Bellamy achieves sequential mating by having the male ground pins protrude farther out from a connector than the signal male pins. We have found that this makes the male ground pins more susceptible to bending or other damage, often resulting in damage that necessitates replacement of the entire cable.